A helical compression spring has an outer diameter between 15 and 50 mm. The helical compression spring having a helically coiled steel wire. The diameter d of the steel wire is between 2 and 5 mm. The steel wire contains a steel alloy having between 0.8 and 0.95 wt % C; between 0.2 and 0.9 wt % Mn; between 0.1 and 1.4 wt % Si; between 0.15 and 0.4 wt % Cr; optionally between 0.04 and 0.2 wt % V; optionally between 0.0005 and 0.008 wt % B; optionally between 0.02 and 0.06 wt % Al; unavoidable impurities; and the balance being iron. The steel alloy has a carbon equivalent higher than 1. The carbon equivalent is defined as: C wt %+(Mn wt %/6)+(Si wt %/5)+(Cr wt %/5)+(V wt %/5). The microstructure of the steel wire in the helical compression spring is drawn lamellar pearlite.

Platinum-nickel-based ternary or higher alloys include platinum at about 65-80 wt. %, nickel at about 18-27 wt. %, and about 2-8 wt. % of ternary or higher additions that may include one or more of Ir, Pd, Rh, Ru, Nb, Mo, Re, W, and/or Ta. These alloys are age-hardenable, provide hardness greater than 580 Knoop, ultimate tensile strength in excess of 320 ksi, and elongation to failure of at least 1.5%. The alloys may be used in static and moveable electrical contact and probe applications. The alloys may also be used in medical devices.

An upper-extremity prosthetic is adapted to engage with an athletic ball. The prosthetic includes one or more springs that provide energy return as a user is throwing the ball using the prosthetic. The springs can have a conductivity that changes in relation to an amount of strain or deformation of the spring. The change in conductivity can be used to provide haptic feedback to the user so the user can sense the amount of force being applied to throw the ball. In some embodiments, the springs are made by a multi-material 3D printing (additive manufacturing) process and include a first material that is electrically non-conductive and a second material that electrically conductive. In some embodiments, the prosthetic also includes one or more cantilevered springs that are also adapted to engage with the ball and to provide energy return while throwing the ball.

A 3D printed additively manufactured (AM) elliptical bifurcating torsion flexure assembly system includes a base section; elliptical bifurcating torsion springs, each including a bifurcated legs section supported by the base; a bifurcated elliptical torsion spring section contiguous with the bifurcated legs section; and a single upper section contiguous with the elliptical torsion spring section. The single upper section includes a connection component, and the device material includes Hot Isostatic Pressing (HIP) heat-treated Ti6Al4V. The elliptical bifurcating torsion flexure assembly is printed as one part by a 3D additive manufacturing process, and the bifurcation maintains consistent balance while being torqued. The stiffness-spring rate of the device is at least partly controlled by varying cross-sectional shape and diameters by the 3D additive manufacturing printing.

A steel wire which has an excellent fatigue limit when made into a spring is provided. A chemical composition of the steel wire according to the present embodiment consists of, in mass %, C: 0.53 to 0.59%, Si: 2.51 to 2.90%, Mn: 0.70 to 0.85%, P: 0.020% or less, S: 0.020% or less, Cr 1.40 to 1.70%, Mo: 0.17 to 0.53%, V: 0.23 to 0.33%, Cu: 0.050% or less, Ni: 0.050% or less, Al: 0.0050% or less, Ti: 0.050% or less, N: 0.0070% or less, Ca: 0 to 0.0050%, and Nb: 0 to 0.020%, with the balance being Fe and impurities. In the steel wire, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 500 to 8000 pieces/μm.sup.2.

A steel wire for a spring includes a steel wire that has Ca or Na adhered thereto in an amount of 0.2 g/m.sup.2 or less. The steel wire has an oxide film on a surface thereof, and the oxide film has a thickness of, for example, from 2.0 μm to 20 μm.

An SMA-STF based viscous damper includes a first connector, a piston rod, a piston which is sheathed on the piston rod; a damping cylinder; first and second end covers which are respectively provided at two sides of the damping cylinder; a second connector which is fixedly connected to the second end cover; and first and second SMA springs which are respectively sheathed on the piston rod. The damping cylinder has first and second damping cavities between which the piston is arranged. One end of the piston rod passes through the first end cover and is connected to the first connector, and the other end passes through the second connector. The first and second SMA springs are respectively held in the first and second damping cavities in an elastic state. The first and second damping cavities are respectively filled with the STF.

A stabilizer formed by using a metal bar having a solid structure and configured to reduce a displacement between right and left wheels, including a torsion part extending in a vehicle width direction, being capable of a torsional deformation, and having a diameter of 10 to 32 mm, is provided. The stabilizer has a chemical composition containing at least C: 0.15% by mass or more to 0.39% by mass or less, Mn, B, and Fe, and also has a metal structure 90% or more of which is a martensite structure.

An upholstery spring comprises a steel spring wire made of a microalloyed steel and a color indicator arranged thereon at least in some regions, the microalloyed steel containing between 0.004 to 0.015 wt.-% of one or more alloy elements. The invention further relates to a method for producing an upholstery spring, a mattress or a piece of upholstered furniture having such an upholstery spring.

A variable-stiffness actuator includes a shape-memory member that increases in stiffness on heating, a heating member arranged to surround the shape-memory member along a longitudinal axis of the shape-memory member, and a heat transmitting medium arranged to surround the heating member along a longitudinal axis of the heating member. The heating member generates heat in response to supply of a current, so as to heat the shape-memory member. The heat transmitting medium is deformed to decrease an inner diameter of the heat transmitting medium to come into contact with the heating member, so as to cool the heating member. The heat transmitting medium is deformed to increase the inner diameter to come out of contact with the heating member.